1. Field
The present invention relates to pressure safety valves and more specifically to automatic pressure valves used with swimming pools and spas to relieve suction pressure in drains as necessary to avoid injury.
2. Prior Art
Pools typically have a single drain at their bottom to remove water from the pool which is then circulated through a pump and filter before it is returned to the pool. There have been a number of very serious injuries caused by the use of single drains in swimming pools. The suction in the drain has held children under the water resulting in drowning. In other instances, children sitting on the drain have been disemboweled by the suction force of the pump coming through the drain. Prior art attempts to prevent this include placing two drains at the bottom of a pool so that if one is closed off, the water is drawn through the second drain, thereby preventing the build up of excessive suction at the closed off drain. This arrangement permits a person held to a drain to pull themselves away from it more easily and with little or no damage. However, the problem remains with many single drain pools that have their drains set in concrete. A second drain could be installed in such pools, but usually at great expense because it often requires the breaking up of the bottom of the pool to install the second drain. As a result, virtually none of the existing single drain pools have been retrofitted in this manner and there remains a need to provide an affordable system for preventing such injuries.